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MG Midget and Sprite Technical - Roll Bar Fitting Problem

The Safety Devices roll bar for my 1967 Austin Healey Sprite Mk IV arrived this week.

When I tried to fit the bar I found that the rear bracing bars foul the original seat belt mounting points. The protruding belt mounting stop the bar's mounting bracket from fitting snugly against the body shell. Even if the bar fitted snugly, it would not be possible to fit the seatbelt.

Grinding back the belt mounting point would provide the necessary clearance but I am reluctant to remove material and risk weakening the mounting. The front face of the wheel arch, adjacent to the ledge that the main hoop sits on, has been repaired by 'plating' some time in the past. This means that the front hoop sits a few millimetres further forward than originally intended but I don't think this makes much difference as moving the bracing bars back would bring them more directly in line with the seat belt bolt holes.

Please see the attached pictures that illustrate the problem.

The bar supplied is the correct one according to SD's website's roll cage selector (RBN006S 5SSS)but I am wondering whether there is a slightly different design for cars with these seat belt mounting points.

I am intending to do a bit of hill climbing and have a four point harness ready to go in when the bar is in place. I had originally hoped to get a bar with a built in harness bar but didn't want to wait several months for the supplier's next delivery.

I would be very grateful for any advice you can offer.

Incidentally - the brown in the pics is not rust - it's evostick - and the black is a mixture of cheap carpet and one of the Sprite's many previous colours - the red is original, it has also been black, 'sand' for a while and is currently maroon!

Colin




Colin Mee

If it were me I'd send it back and ask if they could make a Sprite/midget roll bar to the John Aley/Aleybars Design - either with a removable diagonal or a fixed digonal and have the harness bar fitted.

The bar you have is the Safety Devices design for the Sprite/Midget which in my opinion was never as nice as the Aley design. Safety Devices bought out Aleybars many years ago and so will have the jig for it though whether the jig and country of fabrication is the same I'm no longer sure.
Daniel Stapleton

Thanks Daniel.

Sadly SD seem to be the only affordable option for and FIA approved bar at present. They only nominate two suppliers and only one of them would supply!

I have already reported the problem to SD so when they reply I'll ask them about the Aley bar option. I do know that the bar I have came from somewhere overseas, hence the long wait for the next batch.

Also - I've been intending to get hold of a copy of the Sprite/Midget High Performance Manual - I was about to ask if it's worth putting on my birthday present list and then I noticed who the author is, my guess is that you would recommend it!

Colin
Colin Mee

Colin,
for future reference I can recommend Kim Dear (of Magic Midget) as a very helpful trader, for racing bits, I know there are others but I've only dealt with Kim (but not for racing bits) - http://magicmidget.co.uk/
Nigel Atkins

Colin.

We had to do the same to the "junior" car to get it to fit. I have to say that I agree with Daniel in so much as the first race Midget I had was built with an Aley Bar and that one seemed to be a lot better design that the only one you can get currently from SD.

It held up well to a multiple barrel roll also. In hindsight I should have kept that cage as there were we no kinks or damage to it. Still it's being put to some good use still at the Marshalls training at Snetterton where the car met its demise.

Daniel doesn't need to recommend any particular books as there are quite a few on here who would happily recommend it and I'm one of them.

Andrew


Andrew McGee

i had a Rollcentre cage in mine -

http://www.flickr.com/photos/jc691907/3163755724/in/photostream.

Mounted differently and not a lot of difference in cost probably.
John Collinson

Colin, I've got that SD bar in mine and may have some photo's of the mounting of it on my laptop. I'll have a look tonight and see if I can post them on here.

I ended up cutting the seat belt mount out and plating it up in thicker steel. Then I fitted one harness mount through the floor (with spreader plate underneath) and the other goes through the chassis into the wheelarch. It's just behind the rear 'foot' of the cage and I have the belts crossed over to chafing on the sharp edges of the cage. I needed a longer eye bolt which you can get from Demon Tweeks or similar.

It's not ideal and is at the limit of what is recommended regarding harness angles down from the seat but other than welding onto the cage (which SD say invalidates its certification) there aren't many options.

Never had a scruitineer say anything negative about it though.

John
John Payne

John

Thanks for the advice. The solution you describe is pretty much what I have in mind as my last resort. Reassured that it passes scrutiny.

The car is far from concours but I'm trying to keep the structure as close to original as possible, so I don't want to remove the original belt mounting if I can avoid it.

I'm currently waiting responses from the various other avenues suggested by other posters. Magic Midget don't carry bars but have given a very helpful response.

Regards

Colin
Colin Mee

Although I'm fairly happy with the rear part of the cage I agree it could be a lot better. I think they mounted it there because it is a very strong area. My biggest gripe with SD was that it's taken me 3 years to get hold of the front cage!!

I originally fitted the rear in 2004/05 but then when I did a big rebuild in 2009/10 I tried everywhere to get the front to match. None of the SD stockists had them and SD would only make a batch of 5!! Then about 2 months ago I spotted one on eBay from MGB Hive and snapped it up.

Trouble is I'm not overly happy with the fit of it. I think they've designed it so you can use the original hood and header rail. This means that the part that runs down the A pillars of the screen is about 2-3 inches away from it. It looks very close to your head - and I sit quite well back!

It's very well made and fits everywhere else ok but for use without a crash helmet and full harnesses I'd say its dangerous.

I'm not going for the SD door bars either. The way they mount is a bit agricultural and they are way too expensive. I'm going to use some OMP ones I think.

I'll be back later with some photos hopefully.
John Payne

as a last ditch effort...

can the seat belt attachment be placed on the roll bar its self

I planning to do that in mine when I eventually convert my seat belts to 4 point harness

prop
Prop and the Blackhole Midget

Here's the passenger side all finished as it is now. You can see where the seat belt mount has been cut out and welded up again. Doing that allows the roll bar to sit nicely square to the arch without being put under load. The seat belt mount is just a cheap 3 point that needs to be fitted as the car has to be road legal.


John Payne

Here is the drivers side when I was in the process of fitting some shocks. Again you can see the removal of the seat belt point. The harness eye is fitted (I think it is 2" long) into the chassis and through into the wheel arch where it threads into a spreader plate with captive nut. You can see the other harness mount (eye not fitted) near the bulkhead.

Also, if you look at the bottom left corner of the photo you can see the mounting point I had to weld in to mount the foot of the main hoop of the bar. If this hadn't have been done the top two bolts of the cage were having to pull either the cage or wheel arch in so they met. In fact I dont think they would ever have pulled up hence my making a plinth for the foot to mount on.

Looking back it was quite a big job and took a long time to get right. I seem to remember at the time cursing who had designed it! My car had had work and corrosion in that area so maybe was worse to fit than a decent shell.

Good luck!!


John Payne

Colin I don't think there's an easy answer to mounting of the 3-point belts for road use; the mount will have to be removed for correct installation of the cage. Personally I'd cut it out, plate it like JP's, then weld the threaded boss back into the top part of the arch. For the 4-point belts you would be best to have a harness bar welded onto the cage before fitting it to the car. This will invalidate the FIA homologation cert but that's only important if you intend to race at an event run to full FIA rules i.e.something posh and expensive abroad. If you don't want a harness bar here's a pic of my installation - on the underside of the rear floor there's a lump of 4mm plate about 25 x 10mm from memory.


David Smith

One thing I forgot to ask Colin, what hillclimbing are you thinking of doing? We could do with some more Midgets in the Luffield championship so hopefully its that!

http://www.mgcars.org.uk/mgccsc/


John Payne

Thank you all for all the advice - it's really interesting to see how others have tackled this problem. Most of them are options I've considered so it's handy to see what the finished thing looks like.

For the moment I'm going to wait to see what Safety Devices have to say about it - so far only an automatic reply saying they'll reply within three working days!

As my own welding isn't up to a standard where I would trust it for safety related items like this the photos will be invaluable when discussing the way forward with my local welder.

John - Thanks for the info about the Luffield Championship - one to consider for next year I think. We are complete beginners and, living within earshot of Loton Park, will concentrate on the club events there for now. Plus the quotes for an extension are just landing so someone else in the household will expect a good chunk of my time to be focused on that project!
Colin Mee

to clarify my last post - the reinforcing plate is 25 x 10 cm not mm
David Smith

Thanks Dave - I did wonder when I saw those dimensions - you weren't involved in building the Hubble telescope were you?

That arrangement for the harness mounting points is what I have in mind if I decide to fit the SD bar.

Now that I've been shown it I'm thinking seriously about the RollCentre bar, so I might have an SD bar going spare if the supplier won't take it back!

Incidentally, I have now received a response from SD telling me that as they haven't fitted any in a while they had to check with their agent about their bar and yes, he has to remove the seat belt mounts to make it fit! A shame they don't say that on their website "Roll cage number N006. 6 point bolt-in roll cage .... Rear roll cage mounts to floor riser and rear wheel arches"

Cheers

Colin
Colin Mee

I cant believe they sell a rollbar that doesnt fit except when you grind/plasma-cut your car...
And dont expect them to change anything to the design.
Very frustrating!
Arie de Best

The very obliging guy at RollCentre tells me that the older of their two designs fits without any cutting and welding. It also allows the use of the hood, which their newer one doesn't.

Does anyone have any pics of the older 38mm RollCentre bar in situ? They could only send pics of the newer 41mm bar? Having been stung once I want to take every precaution and make sure it's right before taking the plunge again.

Colin

Colin Mee

Maybe you could Rollcentre if their older design is in fact the John Aley Design? Also if they they a Motor Sports Associaton (MSA) or RAC MSA Recognition number for it.
Daniel Stapleton

Colin

Did you manage to send your old SD rollbar back? if not, I'm on the look out for one and I don't mind doing a bit of cutting / shutting to get it to fit.

I'm also relatively local...

Cheers

Nick
N Parr

Daniel - thanks for the suggestion - again, I've just been assuming it will be MSA compliant but I'll check.

Nick - I'd be happy to sell the bar on to someone who's aware they might need to do other alterations. I'll let you know when I've finally decided - just waiting for a response from RollCentre re Daniel's suggestion!

Colin
Colin Mee

Colin, as if you didn't know already - *never* assume. There's a good reason for the increase from 38 to 41mm OD tube although right now I don't remeber why, think it's due to a change in MSA rules.
David Smith

38 mm tubing for mandatory parts of the cage is ok as long as it is for a cage designed and certified before 1995. Which must be the case with my SD one. It has to have a wall thickness of 2.5mm whereas the 40mm or bigger tubing can be 2mm. (I'm not an expert - I just read it in the blue book!)

I think the bigger tubing looks a bit out of place in a Midget - but then again cages aren't really about looks!

I'm not sure if the removeable diagonal is permitted anymore but like Daniel I think the old Aley bars design is the best.
John Payne

"It also allows the use of the hood, which their newer one doesn't."


Are you f*cking kidding me!!!!!
First they dont fit without having to cut up your car and then you can fit your hood anymore!!!!
And they still want you to pay for it???

Even if the diameter changes you would still expect them to make it fit in the dimensions of hoods and/or hardtops.
Not every racer goes with out top on track.

Is it new rules they have raised the hight of the bar as result that the hood doesnt fit anymore?
If im missing something here then please enligthen me.
Arie de Best

Over here they increase the diameter from 38 to 45 a couple of years ago. Well sourced rumour has it that it arose because a couple of cars when competing overseas (Asia/Pacific somewhere) got their cages knocked back because the local regs required bigger tubing. So the brain surgeons here made the bigger tubing mandatory for everyone! Being a tight fit between hood frame & seat, the 45mm wouldn't allow the operation of the hood. Not an issue for dedicated track cars, but for anyone wanting to use a road car in competition very much an issue.

However, the rules also allow for a free concept cage provided it meets certain loading scenarios (set by FIA I understand). We have just finished (this week) the design of a rollbar for the Midget using 38mm which meets these requirements as well as allowing operation of the hood. Having two sons now qualified mechanical engineers who also understand the requirements and constraints of Midgets was quite handy, as there were a few iterations before we got a configuration which both fitted and met the loadings. Most engineers would have looked at it and probably said it was too hard.
Paul Walbran

Sounds good Paul, where do I get one?!
Andrew F

A bit expensive to ship possibibly. Perhaps I can give you the design once it's had the final MSNZ approval and you could get someone to make it locally. Presumably CAMS will have the same requirements.
Paul Walbran

Yes, I figure shipping could add up, I would be very interested in the design though. I need a bar for my car as I want to fit harnesses and most motorsport events here (for obvious reasons) don't allow use of harnesses without a roll bar.

I too figure that any bar that meets FIA specifications should meet CAMS approval, but I will have to check the process.
Andrew F

ROLLBARS for MOTORSPORT

Sometimes this is a tricky subject even for an MSA scrutineer and it's more complicated for older cars.

First thing is that anyone can make a Roll bar (now called a roll over protection system (ROPS) that is MSA legal by following the drawings in the blue book and tubing specification etc.

Most Sprite/Midget owners don't make their own ROPS but buy one off the shelf or buy a secondhand one that someone else bought off the shelf many years previous from a recognised manufacturer like Aley bars or Safetey Devices (SD). What you will find however, is that the Aley or SD bar pretty much follows the drawings and tubing specification in the blue book anyway. HOWEVER, a manufacturer can deviate from the blue book if they get their bar certificated and they nearly all do. With the Sprite/Midget being an old car and no longer in production most of the new ROPS are built to an old certification as it's not worth the trouble of getting a new design certified. There are of course exceptions especially for the Frogeye.

For UK motorsport and this will be just be racing I'm writing about, unless the event is an International event run to FIA rules (the MG International is Clubmans/National B) there is NO requirement for the ROPS to have a diagonal though most do. It's also the case therefore that it doesn't matter if the diagonal is removable or not and in fact I don't think I've ever seen a racing Sprite/Midget or road car, other than my own, that has the removable diagonal. In fact I've just checked the certificate for my Aley bar and it was certificated with a removable diagonal as well as having the diagonal left to right or right to left!

If I understand the rules correctly the increase in diameter of the tubing is for the home built ROPS. So if a manufacture wants to certify his ROPS with smaller tubing he CAN, though most don't and simply certify broadly along the lines of the latest free build MSA or FIA regulations.

So, if SD have an older design of bar that was certificated with 38mm tubing it's still legal but if they never had it certificated it's not.

The only roll bars that are NO LONGER LEGAL (where the rules require a legal bar) are those made from aluminium tubing and I assume those certificates were cancelled or never existed in the first place.

A point to note is that you can have a certificated Aley bar with small diameter tubing but no diagonal that is MSA race legal but not FIA race legal. However, if the organising club have a more stringent/exceeds MSA ROPS requirement (like a diagonal or full cage) in the supplmentary regs your car has to meet that SR to be race legal on the day.

I think the issue about the number of bolt holes in the mounting feet can be found in the archives.

Finally, don't forget some padding and homologated padding is generally only a mandatory requirement for a full International event.

Final, finally, not sure on the ROPS rules for European events at places such as SPA - they may have historically always been aligned to FIA rules and always want a diagonal.




Daniel Stapleton

Sounds like you have it more reasonable than over here. We have to have a rollbar for anything other than an autotest, and it must be full FIA spec diagonal and all, which is a pain for those who also use the cars on the road.
Paul Walbran

RollCentre bar on order - should be with me in a couple of weeks. Slightly apprehensive as I've never managed to view a complete bar installed, just partial shots like Daniel's, though I'm assured it will go in without any unwanted cutting and welding. This one should also have the harness bar that I was too impatient to wait for from SD, though only on the driver's side.

This means that I have a Safety Devices bar with diagonal going spare - unused and still in most of it's factory wrapping. Nick, if you're still interested do you want to drop me a line? Likewise anyone else who's in the market for an SD bar.

Colin
Colin Mee

RollCentre bar received and fitted! One happy Sprite owner!

Just the padding to fit and we're off. The passenger seat will get its harness when I've sorted a problem with the sill mounting.

We should have given it its first run out at the Loton Park test days last weekend but two foot of snow on the track put paid to that! Doing our best to be patient and ready to go for the first competition in a couple of weeks.

I would have posted sooner if some clot hadn't snagged the overhead phone line and deprived the neighbourhood of phone and internet for over two weeks! Quite a lot of BBS catching up to do!

Colin


Colin Mee

two weeks ! wow have you missed some information on bearings !!

the line will probably melt down with all the info it'll have to download for you to see it all, I suggest you take a toilet break now to be comfortable
Nigel Atkins

Looks good Colin. I can see why SD went for the rear mounts where they did though, much stronger than on top of the inner arch. Wouldn't put me off though, all in all yours looks the better design and has a built in harness bar which is a massive bonus. Wish I'd gone for that 8 years ago!

Just fitted my front SD cage last week, I'll try and post some photo's of it at the weekend.

John Payne

John, does that fit under the hood, or do you have to run with it off?
Paul Walbran

Hello Paul, the rear cage definitely worked with the hood (tight though) but I'm running with a hardtop now. I think it would be ok as the only reason I can see for the front part of the bar to be so far back from the top of the screen/A posts is to make room for the header rail.

I seem to remember when I looked into it years ago that the SD full cage worked with a softop and that there were photo's posted on here of a car in Northern Ireland showing it. Might be worth a trawl through the archives.

You've probably seen my car at Silverstone when you did the sprint a few years ago.
John Payne

Hi Colin,

I'd be grateful if you could e-mail me a copy of the photo you posted above and also in the e-mail tell me the diameter of the roll bar's tubing.

Thanks

Daniel
Daniel Stapleton

And my e-mail is daniel1312dotataol.com and remove the dot at replacing with @
Daniel Stapleton

Cheers John, though my kids tell me I wouldn't have a show of remembering anything ... my excuse would be that it was raining for two of the years I've done the sprint, I can remember that and that it was lots of fun in the wet :-)
Paul Walbran

Colin

What was the model number of the Rollcentre rear cage that you ended up fitting (2nd April, 22:03 message and picture) please?
I guess this is the 'older design' you mentioned? And it fits under the hood and hardtop?

Just what I am looking for. Unless anyone has got an Aleybars rear cage (not aerobar) either with fixed diagonal or removable diagonal.

I note that Rollcentre have supplied roll cages for Sebring Sprite replicas (see picture on: http://sebringsprite.com/946JJO.html) and Safety Devices: http://sebringsprite.com/andychaffeyrep.html which is a standard Midget item [later non-Aleybars design?]).

The online forum for the Midget and Sprite Challenge (UK racing circuit series) would have been a great place to ask for roll age info - but alas it seems U/S.

Best wishes
Mike

Mike Wood
M Wood

Mike

The bar I fitted is the older one which is labelled as the 'Midget National Spec'.

Here's what RollCentre told me before I bought it:
,"...we can do 2 types of bolt in rear cage for the Midget ..., The first one is the old style National spec made out of 38mm CDS, the main hoop mounts on the ledge in front of the rear wheel arch & the rear stays mount on top of the wheel arch, that one should clear the seat belt mounts, ....
The later design rear cage we do is made out of 41mm CDS, The main hoop does mount on the floor by the sill & the rear stays mount further back they are bent with inverted V diagonals in the back... it was designed to fit with a hard top or no roof at all it wont fit with a soft top because the rear stays wont allow the hood to fold back"

The weather was too good to have a roof on when I took it out for a run this weekend but the hard top has been on with no problem. We've not tried the soft top yet but I suspect there will be better clearance - See Dave Stapleton's photo earlier in the thread.

The long term plan is to fit racing seats. I'm not sure what vintage the current seats are (70s I think), but they seem relatively wide and I think I would have had problems with the floor mounted main hoop preventing the seat from going back fully. I'm also not sure whether the later hoop conflicts with the seat belt mounts in the sills.

First time in front of the scrutineers this weekend, so fingers crossed! I'll let you know if I have any problems!

Colin
Colin Mee

Hi

I have located an Aleybars rear rollcage with removeable diagonal just like the one in Daniel's picture above and in his book.

My questions, any answers please?
1. What number do I quote to the MSA to get a copy of the rollcage certificate?
&
2. Any tips on mounting the cage? I have no mounting plates so need to fabricate some and weld them in.

I do realise I need to read the current rule book - MSA Blue Book - as the car is going to be used for speed events.

It has been a while since I installed a rollcage (in a 1970s Talbot Sunbeam) and since then the three mounting bolt per foot requirement has come in for new cages - am I correct that I stick with the current number of mounting holes (2) on an old certified cage, rather than trying to squeeze in another bolt and possibly modifying the cage as far as a scrutineer might see it - therefore potentially invalidating its MSA certification and it not then meeting current new spec in terms of tube diameter and mounting feet place area etc (car in road car claases too).

Thanks
Mike
M Wood

Hi

I have located an Aleybars rear rollcage with removeable diagonal just line the one in Daniel's picture above and in his book.

My questions
1. What number do I quote to the MSA to get a copy of the rollcage certificate?

2. Any tips on mounting the cage? I have no mounting plates so need to fabricate some and weld them in.

I do need to read the current rule book - MSA Blue Book - as the car is going to be used for speed events.

It has been a while since I installed a rollcage (in a 1970s Talbot Sunbeam) and since then the three mounting bolt per foot requirement has come in for new cages - am I correct that I stick with the current number of mounting holes (2) on an old certified cage, rather than trying to squeeze in another bolt and possibly modifying the cage as far as a scrutineer might see it - therefore potentially invalidating its MSA certification and it not then meeting current new spec in terms of tube diameter and mounting feet place area etc (car in road car claases too).

Thanks
Mike
M Wood

Mike

I believe that the RollCentre bar is the same as the Aley bar. I may be wrong but I think RollCentre bought the rights or took over the original company. If this is the case, there is the remote possibility that you RollCentre might be able to supply a certificate.

Bars of the smaller diameter are allowed if they were cerified before a certain date. I made sure that RollCentre included a copy of the certificate when I bought my bar. I keep it with my documents to have it handy at scrutineering but I have never been asked about the bar or had to show the certificate - the RollCentre sticker and serial number on the bar probably help as they don't have a lot of time to do what they need to do.

You can download the Blue Book from the MSA website. Here's a link to the section dealing with ROPS (Roll Over Protection Systems): http://www.msauk.org/assets/156-195commonregulationsforcompetitorssafetyk-3.pdf

Modifying a Roll bar is a very strict No-No, unless you've got all the calcs plus a spare 1000 for MIRA to carry out an assessment and certify it for you.

For Speed events Roll bars are not compulsory for Roadgoing Production classes but they are recommended - here's a link to the Speed section: http://www.msauk.org/assets/156-195commonregulationsforcompetitorssafetyk-3.pdf

If you go to spectate at any Speed events, have a word with a scrutineer or find out if there's one living near you, their contact details are in the Blue Book.

I hope you find a satisfactory solution so that you get to enjoy your Spridget in a hillclimb or sprint - it's great fun and a great, friendly bunch of folk.

Colin
C Mee

Mike, I wouldn't bother with a cage cert - I've never been asked for one in 15 years of racing, mostly in Europe and often under FIA rules, nor in the 10 years of speed events before that. This was with 4 different cars.
Yes use 3 bolts on the front and centre legs - the backstays only need 2.
David Smith

Welcome back feom heades everyone ... how did everyone survive hell..this was an olddy but a goody thread...long time ago


I got to agree with david,

Just do it right, make it look and perform as it should and no one will question it... the squiteners are to busy and wont get into the weeds...if something is obviously an issue yes then they will say something

If your racing at the top of rhe sport then yes every I and T must be accounted for

Its like local 1/8th mile dirt track racing vs sunday afternoon tv nascrap at 1mile daytona

You have to look at rhe race your in and feel how steict there going to be...the more good ol boy havingfun, lets all get drunk afterwords the less the letter of rhe law applies


The more you know mitt rommney and your state seneror arw on a 1ts name basis, the more the finer detailed points of the rules come into play and how they arw interpreted.


Prop
1 Paper

Colin, David and Prop

Many thanks for your helpful replies.

I am aiming for next season getting the car out.

Colin - how is you season and car mods going?

Best wishes
Mike
M Wood

This thread was discussed between 10/02/2013 and 15/07/2017

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.